"We welcome the decision. It's a positive development. Chief minister Tarun Gogoi has been pursuing the matter for long. In 2008, we, for the first time, wrote to the Centre requesting a CBI probe. Then again last year, the chief minister took up the matter with the Centre," Hussain told a press conference. He added that the state government would extend all possible cooperation in the probe.

However, it is not known yet when the CBI will begin the probe. Senior forest officials said that initially, the CBI was requested to probe all the cases of rhino poaching, but it would not be possible. "So, last year, seven cases were submitted to the investigation agency," one of the officials said.

The state government first moved the Centre for a CBI probe in 2008 when at least 12 rhinos were killed by poachers in state.

Last year, 22 one-horned rhinos were killed by poachers in the state while at least 18 died in the floods in Kaziranga. So far this year, 16 rhinos have been poached in the state.

Hussain also informed that a test flight of an unmanned surveillance aircraft would be conducted in Kaziranga this week. Dehradun-based Wildlife Institute of India's scientist K Ramesh and A Christie Williams of WWF International will conduct the test flight from Monday to Thursday.

The forest minister added as ministry of defence is yet to give clearance for the use of unmanned aircraft, hobby planes would be used during the test flight. "Once ministry of defence gives the clearance, Assam will be the first state in the country to use unmanned aircraft for surveillance of Kaziranga," Hussain said.

He added that the joint director of CBI, Mumbai, Keshav Kumar, will impart training on wildlife crime investigation and forensic sciences to field directors of national parks of the northeast and central India at Kaziranga on April 20.